1. Field
The present invention relates to a drawing apparatus, a drawing program, and a drawing method to draw an image by using a polygon including a triangle.
2. Description of the Related Art
Conventionally, a drawing process, for example a three-dimensional drawing process of drawing a three-dimensional figure, by using a polygon has been known. In this drawing process, a display screen is divided into a plurality of rectangle segments called tiles, and a rasterizing process is performed on each of the tiles. The rasterizing process is a process of drawing a figure by filling the inside of respective vertices of a triangle constituting the figure.
When a display screen is divided into a plurality of tiles, a rectangle circumscribing a triangle is set on the basis of information of vertices of the triangle, and a drawing process is performed on each of tiles existing in the rectangle. In this method, the drawing process is performed also in an area where pixels of the triangle do not actually exist. Japanese Unexamined Patent Application Publication No. 2001-283242 discloses a drawing apparatus to determine whether a triangle to be drawn is included in each tile before a rasterizing process and perform the rasterizing process on only the tiles including the triangle with reference to the determination result.
According to this technique, in the case where a drawing process is performed on only the tiles as a drawing target, a determining process needs to be performed on all tiles to determine whether each of the tiles is a drawing target, in order to specify the tiles as a drawing target.